Description

• A clinical syndrome characterized by fever with signs/symptoms of acute meningeal inflammation (including but not limited to headache, photophobia, neck stiffness, and/or nausea/vomiting)
• Viral meningitis (VM) is the most common cause of aseptic (nonbacterial) meningitis.

Epidemiology

Incidence

• Most common form of meningitis
• Peaks summer to fall in temperate climates (but is year round in subtropical or tropical climates)
  • Nonpolio enteroviruses are the most common cause of VM. Estimated 75,000 VM cases caused by enterovirus annually in the United States.

Prevalence
Varies by geographical location and causative pathogen.

Etiology and Pathophysiology

• In immunocompetent hosts, VM is a rare complication of an acute viral infection like gastroenteritis, mumps, herpes simplex virus (HSV), varicella-zoster virus (VZV), and arthropod-borne viruses.
  • Case reports in the literature indicate that SARS-CoV-2 can also cause VM.
  • In immunocompromised hosts, viral pathogens may also include cytomegalovirus (CMV) and Epstein-Barr virus (EBV).
• 23–61% of VM cases are caused by nonpolio human enteroviruses, typically transmitted via the fecal–oral route.
• Mosquito-borne viruses include West Nile, Zika, chikungunya, dengue, St. Louis encephalitis, and Eastern equine encephalitis viruses. Tick-borne viruses include Powassan virus, Colorado tick fever virus, tick-borne encephalitis virus.
• Recurrent benign lymphocytic (Mollaret) meningitis is generally associated with HSV-2 (80% of cases).

Genetics
None identified

Risk Factors

• Age (most common in children <5 years)
  • Babies under <1 month of age are more likely to have severe disease.
• Immunocompromised host (patients more susceptible to CMV, HSV, and EBV)
• Close contacts of people with VM are unlikely to get VM, but may get the primary viral syndrome.

Geriatric Considerations
Cases of VM in the elderly are rare (most common cause is VZV, HSV); consider alternative diagnoses (e.g., cancer, medication-induced aseptic meningitis).

General Prevention

• Practice handwashing and general hygiene procedures.
• Avoid sharing drinks/cups and silverware with others, especially those who are ill.
• Avoid exposure to mosquitoes and ticks; if outdoors, recommend use of appropriate clothing, DEET, and mosquito nets.

Commonly Associated Conditions

Encephalitis; myopericarditis; neonatal enteroviral sepsis; meningoencephalitis; flaccid paralysis